Digital Signage Network – How does it work?

A digital signage network is the only way to centrally manage content and efficiently administer distributed devices. Meanwhile, networks are almost exclusively used, even if most do not recognize it. Learn in this article what you require for this and what you have to pay attention to.

Digital Signage Network

What does Digital Signage Network mean?

A digital signage network is a classic client-server network. The role of the client is played by playback units consisting of a screen with a network-compatible media player. The server component represents the device and content management system.

Users of digital signage usually used a PC in the past. A software ran on it, which served both for content creation and as a player or so-called projector. The use of PowerPoint, by the way, was not uncommon. Small installations even today use such software.

After low-cost DSL flat rates became widespread, more and more providers began to separate the playback component from the administration component and network them together, starting in the mid-2000s at the latest. The now omnipresent Internet and its established TCP/IP protocol families were the obvious choice for the network.

The Playback Component as Automated Clients

To centrally control and manage the screens installed in different locations, it was necessary to separate the player component. This was the birth of the Digital Signage Player as an autonomous client.

This consists – trivially phrased – of a computer without a keyboard with media player software, with a monitor attached to it. These devices have names like:

The client's tasks consist of evaluating the so-called playlist and executing commands. It receives these in two possible ways:

  • Poll: The player regularly requests new content from the server.
  • Push: The server sends new content directly to the player.

Since many devices in DSL are behind a router with a NAT firewall, which makes direct access complicated, polling usually dominates. Recently, providers have also increasingly used mobile networks. This enables direct administration via push, but also increases the risk of compromise through unauthorized access.

The Device and Content Management as a Server Architecture

Most providers are now using web-based management systems. They are installed on a web server and operated in a web browser. The management systems are often marketed as digital signage cloud or SaaS solutions.

There are companies that offer locally installable software, but that is a discontinued model in my view because it has the following disadvantages:

  • Platform dependency
  • High installation and maintenance effort due to different computer environments.
  • Difficult collaboration and synchronization. Working with multiple people or teams becomes complicated.
  • Scaling is a challenge when the network grows.
  • No interfaces for third-party providers or creator agencies.
  • Inconvenient distribution of playlists, as they must first be uploaded to a server each time they are changed, including their media content.

Locale Installations

Occasionally, we get requests for local installations, especially when customers are skeptical about a digital signage cloud. We offer it in principle and have also implemented it for some customers. However, due to the complex architecture, it only makes sense from a certain volume of end devices or legally required IT guidelines.

The Server Architecture

A web-based digital signage CMS should not be understood as monolithic software, unlike the locally installed application described above. A CMS designed for high scalability operates on distributed servers to scale as requirements grow. But more on that later.

To understand this, let's take a look at the typical architecture for digital signage servers. It roughly consists of the following units:

  1. Database Server: Central collection point for various data
  2. GUI-Server: Displays the user interface
  3. Media Server: Stores the uploaded or generated media such as images, videos, widgets, etc.
  4. Job Server: Responsible for generating content such as templates, video conversions, etc.
  5. Index Server: The players retrieve their indexes from there.

What are the Advantages of a Digital Signage Network?

A digital signage network enables access regardless of time and location. Each screen is controlled individually. Several people can work simultaneously in teams or response hierarchies on the administration of devices and content. Intelligently designed architectures also offer high scalability.

Individual Control

In a digital signage network, each screen is controlled individually. So there is the possibility to include different regional specifics in its program.

Editorial Hierarchies

Larger projects require planning and concepts. This also includes the regular creation of digital signage content. In this case, an agency or team often takes care of that. A web application with finely adjustable user rights makes it possible to digitally map an editorial workflow. Sometimes even a hierarchical structure with a revision history is necessary.

Scalability of the Performance

In the Server architecture paragraph, you learned about the individual server units on which larger management systems are built.

Each of these server units can and must be scaled one day to increase their performance. We divide scaling into two types:

  1. Vertical scaling
  2. Horizontal scaling
Server Robot

Vertical Scaling

Vertical scaling is easy to explain: more RAM, a bigger or faster hard drive, and a higher-performance CPU/GPU! However, this type quickly encounters physical limits, especially with the CPU, and drastically increases the costs above a certain threshold.

Example: A 16 core AMD Ryzen 5950X costs about 500 US$. Its benchmark values (Passmark) is 45,869. To double the speed, you need at least an AMD EPYC 7773X with 64 cores, but it is priced at about 6300 US$ (August 2022). This results in a 12.6 times higher price for doubling the speed.

Horizontal scaling

Horizontal scaling offers a solution to this hardware bottleneck. In this process, additional computers are inserted as nodes. This scaling theoretically enables any increase in performance. There are various scaling models for this.

For a database server, horizontal scaling models are called cluster, master/slave, or master/master. A GUI server might stand behind a load balancer, which offers the user the server that is currently least loaded. Media servers use, so-called content delivery networks (CDN), etc.

But for this to work, the management software has to go along with it. In other words, it has to be planned for when designing the software. Implementing scaling capabilities at a later date usually involves significant reconstruction work, which leads to side effects.

What to consider with a Digital Signage Network?

The three most important points in a digital signage network from a technical aspect are:
  1. Security
  2. Scalability
  3. Interfaces

Security

Unfortunately, the topic of security often opens up abysses in our industry. The search term “digital signage security” has an alarmingly low search volume on Google. The service provider should look after both display devices and management systems for the entire duration of the project.

New technologies also bring new attack vectors. The user's awareness of security must be raised through knowledge. Don't just rely on any ISO certifications that have been thrown around meaningfully in marketing lately. The data centers we use all have ISO 27001 certifications.

But at the end of the day, an overpriced basic IT protection certificate won't help you if your employees use too simple passwords, open dubious mail attachments, and are vulnerable to social engineering. Or if we don't do our job properly. That is, if we don't fix software errors and close security gaps quickly.

Interfaces

To collaborate in distributed teams or agencies, interfaces are a crucial factor. It is not even so much about the so-called APIs or REST interfaces. Even an RSS feed offers itself as a standardized data exchange format. At SmilControl, we rely on the openly documented SMIL standard for the transmission of multimedia presentations.

SMIL allows third-party providers to easily integrate their content into our playlists and even define their individual playback conditions. Without the hassle of non-disclosure agreements and meetings to use an API.

Conclusion

Server Robot

Digital signage networks separate player and management components. As requirements increase, the administration of these networks becomes a complex challenge. Open formats such as SMIL allow highly specialized service providers to focus on just one aspect.


Gravatar Nikolaos Sagiadinos
Author: Niko Sagiadinos
Developer & Co-Founder SmilControl – Digital Signage
Visit me on: LinkedIn or GitHub

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